The purpose of this study is to assess the safety and efficacy of time-restricted feeding (eating within an 8-hour window) for improving physiological function (vascular, motor, cognitive and metabolic function) in healthy middle-aged and older adults.

Overall, the proposed research project has the long-term potential to influence clinical practice by establishing novel therapies for treating multiple domains of age-associated physiological dysfunction and thereby reducing the risk of clinical disease and disability.

Inclusion Criteria:

• Ability to provide informed consent
• Baseline brachial flow-mediated dilation (FMD) < 6%Δ (rationale: non-invasive screening to ensure exclusion of subjects with exceptionally high baseline endothelial function.
• Ability to perform motor and cognitive tests (e.g., can rise from a chair, walk for 2 min, climb 10 stairs)
• Women will be confirmed as postmenopausal (either natural or surgical) based on cessation of menses for >1 year.

Exclusion Criteria:

• Ages <55 years or ≥80 years
• Occupation that requires night-shift work or abnormal hours that would disrupt eating schedule
• Dietary habit of regularly skipping meals, already eating within a ~10 hour window, or any other form of restrictive eating.
• Unable to adhere to an 8 hour eating window for the length of the study period
• Participation in regular vigorous aerobic/endurance exercise (>3 vigorous bouts/week)
• Not weight stable in the prior 3 months (>2 kg weight change).
• Body mass index (BMI) >40 kg/m^2 (rationale: vascular function measurements can be inaccurate in severely obese subjects)
• Current smoking
• Diagnosis of a chronic clinical disease (e.g., coronary artery/peripheral artery/cerebrovascular diseases, diabetes, chronic kidney disease requiring dialysis, neurological disorders or diseases that may affect motor/cognitive functions [multiple sclerosis, Parkinson's disease, polio, Alzheimer's disease, dementia or other brain diseases of aging]), except hypertension and hyperlipidemia.
• Having unstable angina, acute myocardial infarction, coronary angioplasty, or aorto- coronary bypass surgery as defined by the occurrence of an event, symptom, surgery, or change in medication and/or dosage within 3 months prior to enrollment.
• Having thyroid disease that is not controlled by medications or <3 month's use of a particular medication and/or dosage (rationale: uncontrolled thyroid diseases are associated with alterations in vascular function).
• Having past or present alcohol dependence or abuse, as defined by the American Psychiatry Association, Diagnostic and Statistical Manual of Mental Disorders